Burglar alarm



June 24, 1,924; 1 1,498,888

. C. RIST BURGLAR ALARM Fild Jan. 19. 1921 'a a; uumnuuuuummm Patented June 24, 1924.

UNITED STATES CONRAD RIS'I', DE LOS ANGELES, CALIFORNIA.

11".." I V BURGLAR ALARM.

Application filed January 19, 1921.

T 0 L ZZ whom it may concern:

'Be it known that I, CONRAD RIsT, a citizen of the United States of America, residing at the city and county of Los Angeles, in the State of California, have invented certain new and useful Improvements in Burglar Alarms, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to improvements in burglar-alarms, and particularly to improvements in burglar-alarms that are electrically-operated. An object of this invention is to provide an electrically-operated burglar-alarm which will prove simple in construction, comparatively cheap in manufacture and low in cost of installation and re pair, and etficient, reliable, durable and sensitive in operation and use.

Another object vide an electrically-operated burglar-alarm which may be readily placed in operative position and quickly removed therefrom when it is no longer needed for use.

In the drawings illustrating the principle of this invention and the best mode now known to me of applying that principle, Fig. 1 is an edge view or side elevation of the burglar-alarm, the battery and alarm-bell being shown conventionally; Fig. 2- is a front elevation or face view; and Fig. 3 illustrates the base or body member fitted in place in the lock-plate of a door;

From one end of the base-piece or bodymember a, there is punched out a laterallyprojecting lug a; and, from the same face a of the base-piece a, there projects, at the other end thereof, a contact-stud 1) formed with a hole 7) for the reception of one end of the conductor (Z, the other end of which electrically connected with one pole c of the battery 6. The contact-stud 7) is formed with a socket into which is screwed the contact-screw 0, by means of which the conductor d is held in place. The opposite face a of the base-piece a is formed with a series of teeth 7, with which engages the toe-end g of a locking-pawl 7t which is pivotally mounted between a pair of ears 2' that project from the middle of the outer face j of an adjustable slide mounted on the basepiece a (see Figs. 1 and 2). The other end of the pawl or catch it is formed with a head or button it and is forced outwardly or away from the base-piece a by means of a helical spring h, whereby the toe g is held of this invention is pro-" Serial No. 538,358.

in engagement with the teeth f and the slidable contact-carrier j is held in its adjusted position on the base-piece a. One end of the contact-carrying slide is bent outwardly at right angles to the body thereof and away from the base-piece a to form a seat or support 7' upon which is secured, by the fast-ening device 70, a contact-stud m having a hole m for the reception of one end of a conductor a, the other end of which is electrically connected with an alarm-bell p. By means of a contact-screw 0, the conductor a is secured in place in the contact-stud m. By means of a conductor is electrically connected 0 of the battery 6. The fastening device 70 (which, as shown in Fig. 2, is a small screwbolthaving a nut engaging its threaded end) with the other pole is insulated from the seat or support 7' by the insulation j as is also the contact-pin 9" that projects from the base m of the contact-stud m. Secured to a contact-post s by means of the screw 8, is a leaf-spring t, which acts as a circuit make-and-break; that is, when the contact-spring t is pressed against the contact-pin 7", current will flow from the positive pole e of the battery 0 through the conductor (Z, post Z), base-piece a, slide j, stud .9, spring t, pin 7', base m, post at, conductor a, alarm-bell 20, and conductor Q to the negative pole c of the battery e; and, due to the passage of the current through the alarm-bell p, the same will be rung.

The base-piece a is made of comparatively thin metal. As illustrated in Fig. 3, the end of the base piece a that is formed with the lug a is placed against the lock-plate u with the lug a projecting into the lower hole a of the lock-plate a (see also Fig. 1).

y closing the door 12 (which may be closed since the base-piece is so thin), the basepiece a is held in the horizontal. position illustrated in Fig. 3 and projects inwardly into the room. The contact-carrying slide 7' is now slipped over the free inner end of the base-piece a and is pushed therealong towards the door, until the contact spring t is very close to the door o, whereupon the toe g of the catch or dog 71. is allowed to be pressed, by the helical spring it, into engagement with the toothed rack f and locks the slide j in its adjusted position. Should the door o be forced inwardly with the parts in the relative positions shown in Fig. 1, the door a will push the the alarm-bell 7) ample, a step-down transformer or any other source of low-voltage current may be substituted for the-battenya; Again a'buzzer, or any other electrically-operated signalling device capable of giving forth signals of sufficient intensity or loudness, may be used in place of the alarm-bell p, which is shown and intended to .be understood-merely as one form of several suitable alarms.

I claim:

1. A burglar-alarm iincluding' a thin con- 7 tact-stud-carrying baseplatearranged to be fitted in its operative position between a door and the frame thereof and of such thinness as to permit the free opening and closing of the door with the base-plate .in its operative position; a con-taot-stud-earrying slide mounted on the base plate and adjustabletherealong into the path of the door; means for retaining the slide in its adjusted position; and acircuit make-andbreak device mounted on the slide and operable by the door -Wl1GI1'i3l16 same is opened.

2. A burglar alarm inclucling-aithincontact-stud-carrying base plate arranged to be fitted in its operative position between a door and the frame thereof and of such thinness as to permit the free opening and closing of the door with the base-plate in its operative position and formed with a lug for insertion into a lock-plate hole for niaintaining the base-plate in operative position; a contaot-stud-carrying slide mounted on the base-plate and-adjustable therealong into the path of the door; means for retain-' ing the slide in its adjusted position on the base-plate; and a circuit make and-break device mounted on the slide and .operable by the door when the same is opened.

3. A burglar-alarm including a thin baseplate arranged vto be fitted, in itsoperative position, between a door and the frame thereof and of such thinness as to permit the free opening and closing of the door with :the ibase-plate in its operative position and havingone of its faces serrated; a con tactstudcarryingslidemountedon the baseplate and adjustable therealong into .the path of the door; a catch carried by the slide and arranged to engage the serrated face of the base-plate and in its adjusted position on the base-plate; and a circuit make-and-break device mounted on the slide and operable by the door when thesame is opened.

Signed in the presence of the two under signed witnesses atthocity and county of Los Angeles, inthe State of'California, this eleventh day of January, 19-21.

V CONRADRIST.

lVitnesses':

WILLIAM H. GREEN,

VILLIAM T'. HEINLEIN.

to hold the slide 

